Keep info on pre-desugaring expression for better "incorrect .await" suggestion

Keep the `HirId` of `.await`ed expressions so in the case of a `fn` call
on on a sync `fn`, we can suggest maybe turning it into an `async fn`.

compiler/rustc_hir_pretty/src/lib.rs

@@ -1731,7 +1731,7 @@ impl<'a> State<'a> {
                     colons_before_params,
                 )
             }
-            hir::QPath::LangItem(lang_item, span) => {
+            hir::QPath::LangItem(lang_item, span, _) => {
                 self.word("#[lang = \"");
                 self.print_ident(Ident::new(lang_item.name(), span));
                 self.word("\"]");